Build a product or service with ‘network effects’ so people are intrinsically inclined to tell their friends: (e.g. the telephone has a network effect because it’s a worthless product if your friends don’t use it -- it's naturally viral)

Build a product or service that’s so awesome that people are inclined to spread the word

Make it really easy for people to spread the word about your product or service

Use gimmicks to get people to tell their friends. I don't mean 'gimmick' in a bad way but there are tactics you can use that give you a temporary bump in new customers. Though they're not truly viral marketing activities as the increase in customers doesn't continue to spread past a few degrees as a real virus would

That said, Uzi's 8 ways of doing viral marketing are interesting. I'd encourage you to read his post before reading on.

To help me think through his approach, I've applied his 8 methods to my framework above and included an example of each:

1. Network Effects

(1) Inherent Virality – your friends must use the product for it to work (example: the telephone)

(2) Collaboration Virality – the product is more valuable if your friends use it (example: Amazon’s ratings & recommendations system)

2. Make an Awesome Product or Service

(8) Pure Word of Mouth Virality – people tell other people because the product is awesome (example: most of Apple’s products)

As I've said before, viral marketing should be a mostly passive activity -- it's an output of building an amazing product or service. So while all of the above are worthy activities, most of your energy should be spent building that amazing product or service that people can't wait to tell their friends about (see #8 above).